Cambrian-Ordovician boundary and stratigraphic division in the Yaowangshan area, Qingzhou, Shandong Province, China

Due to strong dolomitization, sedimentary structure and fossils in the strata in western Shandong almost all disap- pear, which causes difficulties in the stratigraphic division and correlation and even determination of the Cambrian- Ordovician boundary. Geological survey shows that the Late Cambrian- Early Ordovician strata are completely developed in the Yaowang- shan area, Qingzhou, where dolomitization is relatively weak, conodont fossils are very rich and the section can correlate with the international stratotype section. So the Yaowangshan area is an ideal area for improving the stratigraphic division and defining the stratigraphic boundary between Cambrian and Ordovician.